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Sil A, Goldfine EA, Huang W, Bedzyk MJ, Medvedeva JE, Facchetti A, Marks TJ. Role of Fluoride Doping in Low-Temperature Combustion-Synthesized ZrO x Dielectric Films. ACS APPLIED MATERIALS & INTERFACES 2022; 14:12340-12349. [PMID: 35232012 DOI: 10.1021/acsami.1c22853] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Zirconium oxide (ZrOx) is an attractive metal oxide dielectric material for low-voltage, optically transparent, and mechanically flexible electronic applications due to the high dielectric constant (κ ∼ 14-30), negligible visible light absorption, and, as a thin film, good mechanical flexibility. In this contribution, we explore the effect of fluoride doping on structure-property-function relationships in low-temperature solution-processed amorphous ZrOx. Fluoride-doped zirconium oxide (F:ZrOx) films with a fluoride content between 1.7 and 3.2 in atomic (at) % were synthesized by a combustion synthesis procedure. Irrespective of the fluoride content, grazing incidence X-ray diffraction, atomic-force microscopy, and UV-vis spectroscopy data indicate that all F:ZrOx films are amorphous, atomically smooth, and transparent in visible light. Impedance spectroscopy measurements reveal that unlike solution-processed fluoride-doped aluminum oxide (F:AlOx), fluoride doping minimally affects the frequency-dependent capacitance instability of solution-processed F:ZrOx films. This result can be rationalized by the relatively weak Zr-F versus Zr-O bonds and the large ionic radius of Zr+4, as corroborated by EXAFS analysis and MD simulations. Nevertheless, the performance of pentacene thin-film transistors (TFTs) with F:ZrOx gate dielectrics indicates that fluoride incorporation reduces I-V hysteresis in the transfer curves and enhances bias stress stability versus TFTs fabricated with analogous, but undoped ZrOx films as gate dielectrics, due to reduced trap density.
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Affiliation(s)
- Aritra Sil
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
| | - Elise A Goldfine
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Wei Huang
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- School of Automation Engineering, University of Electronic Science and Technology of China (UESTC), Chengdu, Sichuan 611731, China
| | - Michael J Bedzyk
- Department of Materials Science and Engineering and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Julia E Medvedeva
- Department of Physics, Missouri University of Science and Technology, Rolla, Missouri 65409, United States
| | - Antonio Facchetti
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
- Flexterra Inc., 8025 Lamon Avenue, Skokie, Illinois 60077, United States
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States
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Jeon SP, Heo JS, Kim I, Kim YH, Park SK. Enhanced Interfacial Integrity of Amorphous Oxide Thin-Film Transistors by Elemental Diffusion of Ternary Oxide Semiconductors. ACS APPLIED MATERIALS & INTERFACES 2020; 12:57996-58004. [PMID: 33332113 DOI: 10.1021/acsami.0c16068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Low-temperature solution-processed oxide semiconductor and dielectric films typically possess a substantial number of defects and impurities due to incomplete metal-oxygen bond formation, causing poor electrical performance and stability. Here, we exploit a facile route to improve the film quality and the interfacial property of low-temperature solution-processed oxide thin films via elemental diffusion between metallic ion-doped InOx (M:InOx) ternary oxide semiconductor and AlOx gate dielectric layers. Particularly, it was revealed that metallic dopants such as magnesium (Mg) and hafnium (Hf) having a small ionic radius, a high Gibbs energy of oxidation, and bonding dissociation energy could successfully diffuse into the low-quality AlOx gate dielectric layer and effectively reduce the structural defects and residual impurities present in the bulk and at the semiconductor/dielectric interface. Through an extensive investigation on the compositional, structural, and electrical properties of M:InOx/AlOx thin-film transistors (TFTs), we provide direct evidences of elemental diffusion occurred between M:InOx and AlOx layers as well as its contribution to the electrical performance and operational stability. Using the elemental diffusion process, we demonstrate solution-processed Hf:InOx TFTs using a low-temperature (180 °C) AlOx gate dielectric having a field-effect mobility of 2.83 cm2 V-1·s-1 and improved bias stability. Based on these results, it is concluded that the elemental diffusion between oxide semiconductor and gate dielectric layers can play a crucial role in realizing oxide TFTs with enhanced structural and interfacial integrity.
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Affiliation(s)
- Seong-Pil Jeon
- School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 06980, Korea
| | - Jae Sang Heo
- Department of Medicine, University of Connecticut School of Medicine, Farmington, Connecticut 06030, United States
- School of Advanced Materials Science and Engineering and SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Korea
| | - Insoo Kim
- Department of Medicine, University of Connecticut School of Medicine, Farmington, Connecticut 06030, United States
| | - Yong-Hoon Kim
- School of Advanced Materials Science and Engineering and SKKU Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Korea
| | - Sung Kyu Park
- School of Electrical and Electronics Engineering, Chung-Ang University, Seoul 06980, Korea
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Zhuang X, Patel S, Zhang C, Wang B, Chen Y, Liu H, Dravid VP, Yu J, Hu YY, Huang W, Facchetti A, Marks TJ. Frequency-Agile Low-Temperature Solution-Processed Alumina Dielectrics for Inorganic and Organic Electronics Enhanced by Fluoride Doping. J Am Chem Soc 2020; 142:12440-12452. [PMID: 32539371 DOI: 10.1021/jacs.0c05161] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The frequency-dependent capacitance of low-temperature solution-processed metal oxide (MO) dielectrics typically yields unreliable and unstable thin-film transistor (TFT) performance metrics, which hinders the development of next-generation roll-to-roll MO electronics and obscures intercomparisons between processing methodologies. Here, capacitance values stable over a wide frequency range are achieved in low-temperature combustion-synthesized aluminum oxide (AlOx) dielectric films by fluoride doping. For an optimal F incorporation of ∼3.7 atomic % F, the F:AlOx film capacitance of 166 ± 11 nF/cm2 is stable over a 10-1-104 Hz frequency range, far more stable than that of neat AlOx films (capacitance = 336 ± 201 nF/cm2) which falls from 781 ± 85 nF/cm2 to 104 ± 4 nF/cm2 over this frequency range. Importantly, both n-type/inorganic and p-type/organic TFTs exhibit reliable electrical characteristics with minimum hysteresis when employing the F:AlOx dielectric with ∼3.7 atomic % F. Systematic characterization of film microstructural/compositional and electronic/dielectric properties by X-ray photoelectron spectroscopy, time-of-fight secondary ion mass spectrometry, cross-section transmission electron microscopy, solid-state nuclear magnetic resonance, and UV-vis absorption spectroscopy reveal that fluoride doping generates AlOF, which strongly reduces the mobile hydrogen content, suppressing polarization mechanisms at low frequencies. Thus, this work provides a broadly applicable anion doping strategy for the realization of high-performance solution-processed metal oxide dielectrics for both organic and inorganic electronics applications.
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Affiliation(s)
- Xinming Zhuang
- State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Science and Technology, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, China.,Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Sawankumar Patel
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Chi Zhang
- Department of Materials Science and Engineering, The NUANCE Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Binghao Wang
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Yao Chen
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Haoyu Liu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States
| | - Vinayak P Dravid
- Department of Materials Science and Engineering, The NUANCE Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Junsheng Yu
- State Key Laboratory of Electronic Thin Films and Integrated Devices, School of Optoelectronic Science and Technology, University of Electronic Science and Technology of China (UESTC), Chengdu 610054, China
| | - Yan-Yan Hu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, United States.,Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Wei Huang
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
| | - Antonio Facchetti
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States.,Flexterra Corporation, 8025 Lamon Avenue, Skokie, Illinois 60077, United States
| | - Tobin J Marks
- Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, Illinois 60208, United States
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Liang X, Liu L, Cai G, Yang P, Pei Y, Liu C. Evidence for Pseudocapacitance and Faradaic Charge Transfer in High-Mobility Thin-Film Transistors with Solution-Processed Oxide Dielectrics. J Phys Chem Lett 2020; 11:2765-2771. [PMID: 32191479 DOI: 10.1021/acs.jpclett.0c00583] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In developing low-power electronics, low-voltage transistors have been intensively investigated. One of the most important findings is that some high-k oxide gate dielectrics can lead to remarkable enhancement of apparent mobility in thin-film transistors (TFTs), which is not clearly understood. Here, we investigate InOx TFTs with solution-processed AlOx dielectrics. At very low frequencies (<1 Hz), the AlOx films feature strong voltage-dependent capacitance. Also, cyclic voltammograms show clear features of surface-controlled Faradaic charge transfer. The two independent experiments both point to the formation of pseudocapacitance, which is similar to the mechanism behind some supercapacitors. A physical model including charge transfer is established to describe ion distribution. The charge transfer is probably related to residual hydrogens, as revealed by secondary-ion mass spectroscopy. The results provide direct evidence of the formation of pseudocapacitance in TFTs with high apparent mobilities and advance the understanding of mechanisms, measurements, and applications of such TFTs for low-power electronics.
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Affiliation(s)
- Xiaoci Liang
- The State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Ling Liu
- The State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Guangshuo Cai
- The State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Peng Yang
- The State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
| | - Yanli Pei
- The State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
- Department of Electronic Communication and Technology, Shenzhen Institute of Information Technology, Shenzhen 518172, People's Republic of China
| | - Chuan Liu
- The State Key Laboratory of Optoelectronic Materials and Technologies and the Guangdong Province Key Laboratory of Display Material and Technology, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
- State Key Lab of Silicon Materials, Zhejiang University, Hangzhou 310027, People's Republic of China
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Heo JS, Jeon SP, Kim I, Lee W, Kim YH, Park SK. Suppression of Interfacial Disorders in Solution-Processed Metal Oxide Thin-Film Transistors by Mg Doping. ACS APPLIED MATERIALS & INTERFACES 2019; 11:48054-48061. [PMID: 31791119 DOI: 10.1021/acsami.9b17642] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The fabrication of high-performance metal oxide thin-film transistors (TFTs) using a low-temperature solution process may facilitate the realization of ultraflexible and wearable electronic devices. However, the development of highly stable oxide gate dielectrics at a low temperature has been a challenging issue since a considerable amount of residual impurities and defective bonding states is present in low-temperature-processed gate dielectrics causing a large counterclockwise hysteresis and a significant instability. Here, we report a new approach to effectively remove the residual impurities and suppress the relevant dipole disorder in a low-temperature-processed (180 °C) AlOx gate dielectric layer by magnesium (Mg) doping. Mg is well known as a promising material for suppression of oxygen vacancy defects and improvement of operational stability due to a high oxygen vacancy formation energy (Evo = 9.8 eV) and a low standard reduction potential (E0 = -2.38 V). Therefore, with an adequate control of Mg concentration in metal oxide (MO) films, oxygen-related defects could be easily suppressed without additional treatments and then stable metal-oxygen-metal (M-O-M) network formation could be achieved, causing excellent operational stability. By optimal Mg doping (10%) in the InOx channel layer, Mg:InOx TFTs exhibited negligible clockwise hysteresis and a field-effect mobility of >4 cm2 V-1 s-1. Furthermore, the electric characteristics of the low-temperature-processed AlOx gate dielectric with high impurities were improved by Mg diffusion originating in Mg doping, resulting in stable threshold voltage shift in the bias stability test.
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Affiliation(s)
- Jae Sang Heo
- School of Electrical and Electronics Engineering , Chung-Ang University , Seoul 06980 , Korea
- Department of Medicine , University of Connecticut School of Medicine , Farmington , Connecticut 06030 , United States
| | - Seong-Pil Jeon
- School of Electrical and Electronics Engineering , Chung-Ang University , Seoul 06980 , Korea
| | - Insoo Kim
- Department of Medicine , University of Connecticut School of Medicine , Farmington , Connecticut 06030 , United States
| | - Woobin Lee
- School of Advanced Materials Science and Engineering and SKKU Advanced Institute of Nanotechnology (SAINT) , Sungkyunkwan University , Suwon 16419 , Korea
| | - Yong-Hoon Kim
- School of Advanced Materials Science and Engineering and SKKU Advanced Institute of Nanotechnology (SAINT) , Sungkyunkwan University , Suwon 16419 , Korea
| | - Sung Kyu Park
- School of Electrical and Electronics Engineering , Chung-Ang University , Seoul 06980 , Korea
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